Outcomes Research in Review

Once-Daily 2-Drug versus 3-Drug Antiretroviral Therapy for HIV Infection in Treatment-naive Adults: Less Is Best?

Cahn P, Madero JS, Arribas JR, et al. Dolutegravir plus lamivudine versus dolutegravir plus tenofovir disoproxil fumarate and emtricitabine in antiretroviral-naive adults with HIV-1 infection (GEMINI-1 and GEMINI-2): week 48 results from two multicentre, double-blind, randomised, non-inferiority, phase 3 trials. Lancet. 2019;393:143-155.



Study Overview

Objective. To evaluate the efficacy and safety of a once-daily 2-drug antiretroviral (ARV) regimen, dolutegravir plus lamivudine, for the treatment of HIV-1 infection in adults naive to antiretroviral therapy (ART).

Design. GEMINI-1 and GEMINI-2 were 2 identically designed multicenter, double-blind, randomized, noninferiority, phase 3 clinical trials conducted between July 18, 2016 and March 31, 2017. Participants were stratified to receive 1 of 2 once-daily HIV regimens: the study regimen, consisting of once-daily dolutegravir 50 mg plus lamivudine 300 mg, or the standard-of-care regimen, consisting of once-daily dolutegravir 50 mg plus tenofovir disoproxil fumarate (TDF) 300 mg plus emtricitabine 200 mg. While this article presents results at week 48, both trials are scheduled to evaluate participants up to week 148 in an attempt to evaluate long-term efficacy and safety.

Setting and participants. Eligible participants had to be aged 18 years or older with treatment-naive HIV-1 infection. Women were eligible if they were not (1) pregnant, (2) lactating, or (3) of reproductive potential, defined by various means, including tubal ligation, hysterectomy, postmenopausal, and the use of highly effective contraception. Initially, eligibility screening restricted participation to those with viral loads between 1000 and 100,000 copies/mL. However, the upper limit was later increased to 500,000 copies/mL based on an independent review of results from other clinical trials1,2 evaluating dual therapy with dolutegravir and lamivudine, which indicated efficacy in patients with viral loads up to 500,000.3-5

Notable exclusion criteria included: (1) major mutations to nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, and protease inhibitors; (2) evidence of hepatitis B infection; (3) hepatitis C infection with anticipation of initiating treatment within 48 weeks of study enrollment; and (4) stage 3 HIV disease, per Centers for Disease Control and Prevention criteria, with the exception of cutaneous Kaposi sarcoma and CD4 cell counts < 200 cells/mL.

Main outcome measures. The primary endpoint was demonstration of noninferiority of the 2-drug ARV regimen through assessment of the proportion of participants who achieved virologic suppression at week 48 in the intent-to-treat-exposed population. For the purposes of this study, virologic suppression was defined as having fewer than 50 copies of HIV-1 RNA per mL at week 48. For evaluation of safety and toxicity concerns, renal and bone biomarkers were assessed at study entry and at weeks 24 and 48. In addition, participants who met virological withdrawal criteria were evaluated for integrase strand transfer inhibitor mutations. Virological withdrawal was defined as the presence of 1 of the following: (1) HIV RNA > 200 copies/mL at week 24, (2) HIV RNA > 200 copies/mL after previous HIV RNA < 200 copies/mL (confirmed rebound), and (3) a < 1 log10 copies/mL decrease from baseline (unless already < 200 copies/mL).

Main results. GEMINI-1 and GEMINI-2 randomized a combined total of 1441 participants to receive either the once-daily 2-drug ARV regimen (dolutegravir and lamivudine, n = 719) or the once-daily 3-drug ARV regimen (dolutegravir, TDF, and emtricitabine, n = 722). Of the 533 participants who did not meet inclusion criteria, the predominant reasons for exclusion were either having preexisting major viral resistance mutations (n = 246) or viral loads outside the range of 1000 to 500,000 copies/mL (n = 133).

Baseline demographic and clinical characteristics were similar between both groups. The median age was 33 years (10% were over 50 years of age), and participants were mostly male (85%) and white (68%). Baseline HIV RNA counts of > 100,000 copies/mL were found in 293 participants (20%), and 188 (8%) participants had CD4 counts of ≤ 200 cells/mL.

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